A powerful storm approaching Northern California was expected to dump heavy rain on the Bay Area and up to 4 feet of snow in some parts of the Sierra before moving out on Thursday.

The National Weather Service warned residents in North Bay areas ravaged by the wildfires in October to be alert for flash flooding.

“We will see precipitation move through the Bay Area through the overnight hours,” Roger Gass, a meteorologist with the weather service in Monterey, said Wednesday. “We can’t rule out a few lingering showers into” Thursday.

Up to 2 inches of rain was expected to fall in the burned areas of Napa and Solano counties. A flash-flood watch for the burn-scar areas was in effect until at least Thursday morning, as the weather service warned of possible debris flows.

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Santa Rosa officials were keeping an especially close eye on the hilly Fountaingrove neighborhood, which was destroyed by the Tubbs Fire early Oct. 9. The blaze damaged storm drains, raising the chance that heavy rains could cause sinkholes or landslides, said Ben Horenstein, director of the city Water Department.

The Lake Tahoe area was expected to be blanketed by 2 to 4 feet of snow above the 8,000-foot level, a boon for ski resorts planning to open Friday, including Squaw Valley Alpine Meadows and Heavenly Mountain Resort.

A winter storm warning went into effect at 4 a.m. Wednesday and will last until Friday.

Scott McGuire, a meteorologist with the National Weather Service in Reno, said gusts in the Sierra will range from about 60 mph in the Lake Tahoe area to up to 120 mph along the ridgetops.

“People can plan on difficult travel conditions and expect damage to trees and power lines,” McGuire said.

Once the storm blows through, conditions should be optimal for skiers and snowboarders, said Coop Cooper, a spokesman for Heavenly Mountain Resort and Kirkwood Mountain Resort.

“This is the perfect storm for us to get the season going,” Cooper said. “For the weekend, it’s ideal conditions because this will mix Mother Nature’s natural snow with the man-made snow we are making.”

In San Francisco, forecasters expect a little more than an inch of rain, and Oakland and San Jose are expected to get close to an inch. Temperatures will remain in the 60s for most of the region, Gass said.

The storm system will move out of the Bay Area by Friday. After that, there will be clear skies and cooler temperatures into the weekend, Gass said.